The present invention generally relates to the field of electronic electricity meters. More specifically, the present invention relates to a power supply for providing power to operate the electronic monitoring circuitry contained within an electronic electricity meter. An electricity metering system monitors power lines to derive polyphase input representations of voltage and current. Because electrical uses by different consumers can vary significantly, a typical utility providers require different meters for monitoring various primary voltages. Currently, available meters exist that utilize both electromechanical and electronic circuitry to monitor the voltage and current consumption.
It has been recognized that a solid state electronic electricity meter provides a more dynamic device and a more accurate measurement of the energy consumption. However, the microprocessor-based monitoring circuitry used within electronic electricity meters requires the provision of one or more supply voltages to operate the monitoring circuitry. Internal power supplies that are capable of generating a relatively constant DC voltage from the three-phase AC line voltage being monitored have been used for this purpose. Since electric utility companies require meters for a variety of different primary AC line voltages, it has been necessary to provide power supplies that have individualized components to generate the microprocessor supply voltages from the variety of primary voltages.
Various circuit designs, such as shown in U.S. Pat. No. 5,621,629, have been developed to provide a single meter that is capable of metering electrical energy associated with primary voltages that vary over a wide range. Although switching power supplies and voltage dividers are known for use in an electronic electricity meter, drawbacks exist with the currently available power supplies. Therefore, it is an object of the present invention to provide a power supply for an electronic electricity meter that addresses problems associated with currently available power supplies.